Umar Khan | Iqra University IU (original) (raw)

Papers by Umar Khan

This study was done on the stomach contents and feeding biology of the two catfishes of Subfamily... more This study was done on the stomach contents and feeding biology of the two catfishes of Subfamily Schilbeina; Eutropiithys vacha and Clupisoma naziri. This study was conducted from summer till winter 2011. The food items of C. naziri were small aquatic and terrestrial insects and is Corni-ommnivorus. However, E. vacha predominantly feeds on small fishes as well as aquatic and terrestrials insects, and thus predominantly is Piscivorouous. The number of gill rackers in C. naziri was found more than E. vacha. In addition to this, the gill rackers of C. naziri were also found large and pointed. This difference of gill rackers reveals that C. naziri has strong sieve which can strain more efficiently than E. vacha. Due to efficient straining, various and more types of algae were investigated from the stomach of C. naziri. The genera of Algae which were found in C. naziri were Lyngbya (29.6%), Oscillatoria (16.9), Cymbella (9.2%), Syndra (5.6%), Diatoma (14.8), Ulothirx(9.2%) and Scenedesm...

ABSTRACT This study was carried out from summer till winter of 2011 to find out the diet of adult... more ABSTRACT This study was carried out from summer till winter of 2011 to find out the diet of adult Catfish, Eutropiichthys vacha. A total of 216 fish stomach contents were analyzed to find out food items of this fish. Out of these, 63 (29.2%) stomachs were empty and the remaining 153 (70.8%) fish stomachs had prey. Stomach contents of 58% samples had small fishes, 36.8% had small aquatic and terrestrial insects and the remaining 5.2% had shrimps. In addition phytoplankton, consisting of Lyngbya and Oscilatoria and Diatoma (Bacillariophyceae), were also found as an important ingredient of diet of this fish. Some contents of phytoplankton could not be identified due to its partial digestion and change of colour. The feeding intensity was also studied to find out any cessation of feeding. The study confirmed that there is no discontinuation of feeding in this fish from summer to winter, as the weight of stomach contents remained unchanged during the study period. The structure of mouth, dentation, gills and stomach were also studied as they are associated with food intake. Freshwater catfish (Eutropiichthys vacha) is an economically important fish of the family Schilbidae. This fish has gained popularity among consumers due to its high nutritional value (Hasan et al. 2002). It is one of the most important food fish in Khyber Pakhtunkhwa (KP) province of Pakistan. E. vacha is a potamodromous fish, i.e., migrates from one river to another for spawning and nursery ___________________________

$Research paper thumbnail of A clinic-based study of refractive errors, strabismus, and amblyopia in pediatric age-group$

Journal of Family and Community Medicine, 2015

UA. A clinic-based study of refractive errors, strabismus, and amblyopia in pediatric age-group.

National Academy Science Letters, 2015

In this article, two types of problems are investigated. The flow and heat transfer over: (1) a s... more In this article, two types of problems are investigated. The flow and heat transfer over: (1) a static flat plate (Blasius problem) and (2) a moving flat plate (Sakiadis problem) are considered. Convective boundary conditions are used to formulate the energy equation. Suitable similarity transform has been employed to reduce the governing nonlinear partial differential equations to a set of somewhat simpler nonlinear differential equations. These equations are then solved numerically by using sixth order Runge-Kutta method. Influences of different emerging parameters on both the problems are presented graphically coupled with comprehensive discussions.

ABSTRACT MHD flow of a Jeffrey fluid in a converging and diverging channel is considered. Study o... more ABSTRACT MHD flow of a Jeffrey fluid in a converging and diverging channel is considered. Study of flows between nonparallel walls has a very significant role in physical and biological sciences. A highly nonlinear differential equation describing the flow of an electrically conducting Jeffrey fluid between oblique walls is obtained by using conservation laws along with similarity transformations. Adomian&#39;s Decomposition Method (ADM) is then employed to determine the solution to the resulting differential equation. A numerical solution is also sought using Runge-Kutta (RK-4) method. Both the solutions are compared and an excellent agreement is found between them. Effects of different dimensionless physical parameters on the flow are demonstrated graphically coupled with comprehensive discussions at the end of the article.

European Journal of Plastic Surgery, 2010

Implant malplacement is the second most common reason for revision and bottoming down is the most... more Implant malplacement is the second most common reason for revision and bottoming down is the most common presentation of implant malplacement. Submuscular biplane relocation was combined with capsulotomies and multilayer capsulorrhaphy when bottoming down was seen following subglandular breast augmentation. Between 2005 and 2009, bottoming down following subglandular mammoplasty was seen in 41 breasts (19 bilateral and three unilateral). Of the 19 patients, 12 had downward transgression of inframammary crease (IMC) alone; this also included a patient with vertical scar mastopexy. Two patients had multiplane malplacements where bottoming down was associated with lateral displacement (telemastia) in one and medial displacement (symmastia) in the other. Two had simultaneous downward transgression of the IMC and nipple areolar complex (NAC) and three had bottoming down with capsular contracture independent of NAC descent. Follow-up of up to 3 1/2 years showed stable IMC and NAC relationship with acceptable results. Dog ear revision was required in one patient when IMC relocation was accompanied with vertical scar mastopexy and one patient needed revision for further relocation and improvement of symmastia. No wound breakdown or periprosthetic infection was seen in their series. Multilayer capsulorrhaphy with submuscular biplane repositioning of implants is a suitable option to correct bottoming down following subglandular augmentation.

Nanoscale, 2015

In this work we have used melt-processing to mix liquid-exfoliated boron-nitride nanosheets with ... more In this work we have used melt-processing to mix liquid-exfoliated boron-nitride nanosheets with PET to produce composites for gas barrier applications. Sonication of h-BN powder, followed by centrifugationbased size-selection, was used to prepare suspensions of nanosheets with aspect ratio >1000. The solvent was removed to give a weakly aggregated powder which could easily be mixed into PET, giving a composite containing well-dispersed nanosheets. These composites showed very good barrier performance with oxygen permeability reductions of 42% by adding just 0.017 vol% nanosheets. At low loading levels the composites were almost completely transparent. At higher loading levels, while some haze was introduced, the permeability fell by ∼70% on addition of 3 vol% nanosheets. † Electronic supplementary information (ESI) available. See

Propulsion and Power Research, 2014

Thermodiffusion effects on stagnation point flow of a nanofluid towards a stretching surface with... more Thermodiffusion effects on stagnation point flow of a nanofluid towards a stretching surface with applied magnetic field is presented. Similarity transforms are applied to reduce the equations that govern the flow to a system of nonlinear ordinary differential equations. Runge-Kutta-Fehlberg method is applied to solve the system. Results are compared with existing solutions that are special cases to our problem. Concrete graphical analysis is carried out to study the effects of different emerging parameters such as stretching ratio A, magnetic influence parameter M, Prandtl number Pr, Lewis number Le, Brownian motion parameter Nb, thermophoresis parameter Nt, nanofluid Lewis number Ln, modified Dufour parameter Nd and Dufour solutal number Ld coupled with comprehensive discussions. Numerical effects of local Nusselt number, local Sherwood number and nanofluid Sherwood number are also discussed.

ACS nano, Jan 23, 2014

Monitoring of human bodily motion requires wearable sensors that can detect position, velocity an... more Monitoring of human bodily motion requires wearable sensors that can detect position, velocity and acceleration. They should be cheap, lightweight, mechanically compliant and display reasonable sensitivity at high strains and strain rates. No reported material has simultaneously demonstrated all the above requirements. Here we describe a simple method to infuse liquid-exfoliated graphene into natural rubber to create conducting composites. These materials are excellent strain sensors displaying 10(4)-fold increases in resistance and working at strains exceeding 800%. The sensitivity is reasonably high, with gauge factors of up to 35 observed. More importantly, these sensors can effectively track dynamic strain, working well at vibration frequencies of at least 160 Hz. At 60 Hz, we could monitor strains of at least 6% at strain rates exceeding 6000%/s. We have used these composites as bodily motion sensors, effectively monitoring joint and muscle motion as well and breathing and pulse.

European Journal of Plastic Surgery, 2014

Background Breast and chest asymmetries have been reported with varying incidences in patients re... more Background Breast and chest asymmetries have been reported with varying incidences in patients requesting augmentation mammoplasty. However, there is a paucity of information regarding the sizes of different implants used, their relative distribution on either side, complications and revision rates in this cohort when compared with primary augmentation mammoplasty using similar size implants. Methods A retrospective data using the Excel spreadsheet was performed. All patients had muscle splitting technique for augmentation mammoplasty in asymmetrical breasts. Patients requiring augmentation with mastopexy, sternal notch to nipple areolar complex level discrepancy of more than 1 cm, and patients having same size implants were excluded from the analysis. Insignificant asymmetries, not noticed by patients, were not chosen for two different size implants. Patients, who chose two different size implants for mammoplasty, were divided into three groups based on the relative difference in the size of different implants used. Results A total of 164 patients had primary augmentation mammoplasty between 2005 and 2011, using two different size implants for augmentation mammoplasty in asymmetrical breasts. Mean age of the patients (n= 164) was 29.2 ± 7.79 years (range 18-50), and 46 (28.0 %) were smokers. Complete data on differential implant sizes used was available in 146 patients. Mean size of the implant on the right (n=146) was 346.27±70.581 cc (range 220-605). The mean size of the implant on the left (n=146) was 333.46±74.419 cc (range 200-655). Out of these 146 patients, 46 (31.5 %) patients had larger implants on the left as compared to 100 (68.5 %) patients on the right. Mean volume difference between the two sides when larger implants were used on left side was 55.76±37.785 cc as compared to 44.35±26.166 cc when larger implants were used on the right side. Low profile combination was used in 2.73 %, moderate size implant combination was used in 9.58 %, mixed profile combination was used in 3.42 % and high profile combination was used in 84.24 % of the patients. Overall revision surgery was performed in three patients (1.8 %), and out of these three revisions, only one (0.6 %) patient needed surgery for volume correction. Conclusions Primary augmentation mammoplasty in asymmetrical breasts using differential size implants is a procedure with low revision rates, provided that strict exclusion criteria are used along with adequate informed consent in this group. Level of Evidence: Level IV, risk/prognostic study.

Proceedings 2007 IEEE International Conference on Robotics and Automation, 2007

This paper presents a novel approach to large view visual servoing in the context of object manip... more This paper presents a novel approach to large view visual servoing in the context of object manipulation. In many scenarios the features extracted in the reference pose are only perceivable across a limited region of the work space. The limited visibility of features necessitates the introduction of additional intermediate reference views of the object and requires path planning in view space. In our scheme the visual control is based on decoupled moments of SIFT-features, which are generic in the sense that the control operates with a dynamic set of feature correspondences rather than a static set of individual features. The additional freedom of dynamic feature sets enables flexible path planning in the image space and online selection of optimal reference views during servoing to the goal view. The time to convergence to the goal view is estimated by a neural network based on the residual feature error and the quality of the SIFT feature distribution. The transition among reference views occurs on the basis of this estimated cost which is evaluated online based on the current set of visible features. The dynamic switching scheme achieves robust and nearly timeoptimal convergence of the visual control across the entire task space. The effectiveness and robustness of the scheme is confirmed in an evaluation in a virtual reality simulation and on a real robot arm with a eye-in-hand configuration.

Journal of Physical Chemistry C, 2008

We found no reference to the Hildebrand parameter (δ T) of ODA in the literature. However it is p... more We found no reference to the Hildebrand parameter (δ T) of ODA in the literature. However it is possible to estimate it via the Hansen parameters of common materials 28. These are three parameters, δ D , δ P and δ H which measure the contributions to δ T from the dispersion interaction, polar interactions and H bonding respectively. These parameters can be associated with different parts of the molecule. For example the δ P and δ H values for alkylamines do not vary much with the number of carbons in the alkyl chain (table S2)

Small, 2011

A commercial thermoplastic polyurethane is identified for which the addition of nanotubes dramati... more A commercial thermoplastic polyurethane is identified for which the addition of nanotubes dramatically improves its mechanical properties. Increasing the nanotube content from 0% to 40% results in an increase in modulus, Y, (0.4-2.2 GPa) and stress at 3% strain, σ(ϵ = 3%) , (10-50 MPa), no significant change in ultimate tensile strength, σ(B) , (≈50 MPa) and decreases in strain at break, ϵ(B) , (555-3%) and toughness, T, (177-1 MJ m(-3) ). This variation in properties spans the range from compliant and ductile, like an elastomer, at low mass fractions to stiff and brittle, like a rigid thermoplastic, at high nanotube content. For mid-range nanotube contents (≈15%) the material behaves like a rigid thermoplastic with large ductility: Y = 1.5 GPa, σ(ϵ = 3%) = 36 MPa, σ(B) = 55 MPa, ϵ(B) = 100% and T = 50 MJ m(-3) . Analysis suggests that soft polyurethane segments are immobilized by adsorption onto the nanotubes, resulting in large changes in mechanical properties.

Science, 2011

Layered transition metal dichalcogenides, such as tungsten disulfide, are exfoliated into atomica... more Layered transition metal dichalcogenides, such as tungsten disulfide, are exfoliated into atomically thin flakes.

PLoS Currents, 2013

Some parts of world, including India observed a recrudescent wave of influenza A/H1N1pdm09 in 201... more Some parts of world, including India observed a recrudescent wave of influenza A/H1N1pdm09 in 2012. We undertook a study to examine the circulating influenza strains, their clinical association and antigenic characteristics to understand the recrudescent wave of A/H1N1pdm09 from November 26, 2012 to Feb 28, 2013 in Kashmir, India. Of the 751 patients (545 outpatient and 206 hospitalized) presenting with acute respiratory infection at a tertiary care hospital in Srinagar; 184 (24.5%) tested positive for influenza. Further type and subtype analysis revealed that 106 (58%) were influenza A (H1N1pdm09 =105, H3N2=1) and 78 (42%) were influenza B. The influenza positive cases had a higher frequency of chills, nasal discharge, sore throat, body aches and headache, compared to influenza negative cases. Of the 206 patients hospitalized for pneumonia/acute respiratory distress syndrome or an exacerbation of an underlying lung disease, 34 (16.5%) tested positive for influenza (22 for H1N1pdm09, 11 for influenza B). All influenza-positive patients received oseltamivir and while most patients responded well to antiviral therapy and supportive care, 6 patients (4 with H1N1pdm09 and 2 with influenza B) patients died of progressive respiratory failure and multi-organ dysfunction. Following a period of minimal circulation, H1N1pdm09 re-emerged in Kashmir in 2012-2013, causing serious illness and fatalities. As such the healthcare administrators and policy planners need to be wary and monitor the situation closely. Funding Statement The study was funded in part by the cooperative agreement between CDC, Atlanta, Georgia (USA) and Indian Council of Medical Research (India). The findings and conclusions of this report are those of the authors and do not necessarily represent the views of the Center for Disease Control and Prevention. Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

Journal of Materials Chemistry, 2011

In this work carbon based nanomaterials in ionic liquids have been studied as potential electroly... more In this work carbon based nanomaterials in ionic liquids have been studied as potential electrolytes for dye sensitised solar cells (DSSCs). Graphene, single wall carbon nanotubes (SWCNTs) and a mixture of graphene and SWCNTs were incorporated into 1-methyl-3-propylimidazolium iodide (PMII) ionic liquid. The resulting quasi-solid state electrolytes were sandwiched between TiO 2 working electrodes and platinum counter electrodes and subsequent DSSCs were fabricated. Graphene based quasi-solid state electrolytes displayed an increase of light conversion efficiencies in the completed DSSC from 0.16% (for pure PMII) to 2.10%. For SWCNTs, the observed light conversion efficiency increased from 0.16% to 1.43% and for the mixture of graphene and SWCNTs the light conversion efficiency improved from 0.16% to 2.50%. This significant increase occurred because the carbon materials serve simultaneously both as charge transporter in the ionic liquids and as catalyst for the electrochemical reduction of I 3 À. It is also expected that there is an ionic liquid mediated self-organisation of graphene and SWNT nanomaterials into structured networks, which provide an efficient electron transfer. Thermogravimetric analysis (TGA) studies showed that these electrolytes are stable up to 300 C.

Composites Science and Technology, 2011